Abstract

Introduction: Parkinson’s disease (PD) can impact enormously on speech communication. One aspect of
non-verbal behaviour closely tied to speech is co-speech gesture production. In healthy people,
co-speech gestures can add significant meaning and emphasis to speech. There is, however, little
research into how this important channel of communication is affected in PD.
Methods: The present study provides a systematic analysis of co-speech gestures which spontaneously
accompany the description of actions in a group of PD patients (N ¼ 23, Hoehn and Yahr Stage III or less)
and age-matched healthy controls (N ¼ 22). The analysis considers different co-speech gesture types,
using established classification schemes from the field of gesture research. The analysis focuses on the
rate of these gestures as well as on their qualitative nature. In doing so, the analysis attempts to overcome
several methodological shortcomings of research in this area.
Results: Contrary to expectation, gesture rate was not significantly affected in our patient group, with
relatively mild PD. This indicates that co-speech gestures could compensate for speech problems.
However, while gesture rate seems unaffected, the qualitative precision of gestures representing actions
was significantly reduced.
Conclusions: This study demonstrates the feasibility of carrying out fine-grained, detailed analyses of
gestures in PD and offers insights into an as yet neglected facet of communication in patients with PD.
Based on the present findings, an important next step is the closer investigation of the qualitative
changes in gesture (including different communicative situations) and an analysis of the heterogeneity in
co-speech gesture production in PD.